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Vulnerabilities

Vulnerability · CVE-2026-33151

Socket.IO is an open source, real-time, bidirectional, event-based, communication framework.

Published Mar 20, 2026 · catalog updated Jun 17, 2026 · Socket.IO is an open

Check if you run it

No confirmed exploitation is on record for CVE-2026-33151. EPSS is 0.65%. Act only if a listed version of Socket.IO is an open is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Socket.IO is an open).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.65%
Remediation
Advisory link
Affected products
cpe socket/socket.io-parser

Socket.IO is an open source, real-time, bidirectional, event-based, communication framework. Prior to versions 3.3.5, 3.4.4, and 4.2.6, a specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory. This issue has been patched in versions 3.3.5, 3.4.4, and 4.2.6.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe socket/socket.io-parserversion unspecified

How to fix CVE-2026-33151

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-33151. EPSS is 0.65%. Act only if a listed version of Socket.IO is an open is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-20: Improper Input Validation; CWE-754. EPSS 0.65%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 20, 2026 · NIST NVD

    Detected

    Socket.IO is an open source, real-time, bidirectional, event-based, communication framework. Prior to versions 3.3.5, 3.4.4, and 4.2.6, a specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory. This issue has been patched in versions 3.3.5, 3.4.4, and 4.2.6.

  2. Jun 17, 2026 · NIST NVD

    Updated

    Socket.IO is an open source, real-time, bidirectional, event-based, communication framework. Prior to versions 3.3.5, 3.4.4, and 4.2.6, a specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory. This issue has been patched in versions 3.3.5, 3.4.4, and 4.2.6.

Sources

  • CVE.orgVulnerability recordCVE-2026-33151

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-33151

    30-day exploitation probability 0.7%

    first.org
  • NIST NVDVulnerability recordCVE-2026-33151

    Socket.IO is an open source, real-time, bidirectional, event-based, communication framework. Prior to versions 3.3.5, 3.4.4, and 4.2.6, a specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited t

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.